Independently and not as an agent of the Government, the Contractor shall exert its best efforts to perform in vivo evaluation of hybrid cells formed by the fusion of chemically-induced sarcomas with C3H fibroblasts. These hybrid cells will be studied for their capacity to influence syngeneic tumor bearing animals so as to alter tumor related morbidity and mortality. Therapeutic effectiveness may be evaluated in combination with other modalities of therapy, including BCG. Appropriate in vitro assays will be conducted to study the immunologic aspects of any therapeutic effect observed in this system.